Weather Service Report


634 
FXUS66 KPQR 292159 AAA
AFDPQR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR 
258 PM PDT FRI APR 29 2016

.SYNOPSIS...POST COLD FRONTAL SHOWERS WILL CONTINUE THIS
AFTERNOON...THEN DISSIPATE TONIGHT. THERE WILL BE A RETURN
TO DRY AND WARM WEATHER OVER THE WEEKEND AND EARLY NEXT WEEK AS UPPER
LEVEL HIGH PRESSURE BUILDS OVER THE PAC NW. OFFSHORE WINDS WILL
DEVELOP ON SUN. A SOUTHERLY SURGE OF MARINE AIR ALONG THE COAST IS
EXPECTED MON. AN UPPER LEVEL TROUGH WILL APPROACH THE COAST TOWARD
THE MIDDLE OF NEXT WEEK...BRINGING WARM SOUTHERLY FLOW ALONG WITH THE
POTENTIAL FOR SHOWERS AND POSSIBLY EVEN SOME THUNDERSTORMS. 

&&

.SHORT TERM....TONIGHT THROUGH MONDAY...
A WEAK COLD FRONT MOVED THROUGH SW WASHINGTON AND NW OREGON
TODAY...BRINGING A PERIOD OF LIGHT RAIN TO MUCH OF THE REGION. THE
STEADIER RAIN IS NOW OVER THE CASCADES. A MODERATELY UNSTABLE AIR
MASS BEHIND THE FRONT IS DRIVING FAIRLY WIDESPREAD SHOWER ACTIVITY
THIS AFTERNOON. BASED ON THE FCST MODEL SOUNDINGS...THE DEPTH OF
CONVECTION DOES NOT LOOK DEEP ENOUGH FOR ANY THUNDERSTORM
DEVELOPMENT. AN UPPER LEVEL RIDGE WILL APPROACH THE COAST
TONIGHT...BRINGING WARMER AIR ALOFT. THIS WILL ACT TO STABILIZE THE
ATMOSPHERE AND CAUSE SHOWER ACTIVITY TO TAPER OFF. A FEW SHOWERS MAY
LINGER OVER THE CASCADES INTO EARLY SAT MORNING.

CLOUDS LINGERING OVER THE CASCADES AND FOOTHILLS AFTER THE OVERNIGHT
SHOWERS MAY BACKBUILD INTO EASTERN PORTIONS OF THE WILLAMETTE VALLEY
EARLY SAT. THE UPPER LEVEL RIDGE AXIS WILL PUSH CLOSER TO THE COAST
SAT. DRY NORTHERLY FLOW TO DEVELOP AT THE LOWER LEVELS...WHICH SHOULD
LEAD TO CLEARING SKIES AND CONSIDERABLE AFTERNOON SUNSHINE. 850MB
TEMPS WILL WARM A FEW DEGREES TO 5-6 C...WHICH SHOULD ALLOW AFTERNOON
HIGHS TO REACH INTO THE MID TO UPPER 60S FOR THE INTERIOR. THE COAST
WILL STAY COOLER IN THE UPPER 50S TO LOW 60S WITH AN ONSHORE
COMPONENT TO THE FLOW.

SUNDAY WILL BE EVEN WARMER AND SUNNIER AS LOW LEVEL FLOW IS MODELED
TO BECOME OFFSHORE DURING THE DAY. 850MB TEMPS INCREASE TO 10 TO 12
C...WHICH COMBINED WITH THE MIXING IN THE LOWER LEVELS DUE TO THE
OFFSHORE FLOW SHOULD ALLOW HIGHS TO CLIMB INTO THE UPPER 70S TO LOW
80S OVER THE INTERIOR. THE OFFSHORE FLOW SHOULD ALSO ALLOW THE COAST
TO WARM UP WELL INTO THE 70S AS WELL. 

A SURGE OF SOUTHERLY FLOW IS MODELED TO DEVELOP ALONG THE COAST SUN
NIGHT INTO MON. THIS WILL BRING INCREASING LOW LEVEL CLOUDS ALONG THE
COAST. TEMPS WILL COOL CONSIDERABLY AT THE COAST AS WELL...WITH SOME
OF THE COOLER MARINE AIR ALSO LIKELY MAKING IT INTO SOUTHERLY
PORTIONS OF THE WILLAMETTE VALLEY AS WELL. HOWEVER NORTHERN PORTIONS
OF THE VALLEY MAY NOT SEE MUCH MARINE INFLUENCE AT ALL...POTENTIALLY
ALLOWING FOR TEMPERATURES TO REACH A FEW DEGREES HIGHER THAN ON
SUNDAY. A SPLITTING UPPER LEVEL TROUGH WILL BE APPROACHING THE COAST
MON...WHICH SOME OF THE FCST MODELS ARE SUGGESTING WILL BRING ENOUGH
MID LEVEL MOISTURE AND INSTABILITY TO GENERATE A FEW SHOWERS OR
THUNDERSTORMS OVER THE LANE COUNTY CASCADES. PYLE

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY. BROAD UPPER TROUGH OVER
THE EASTERN PACIFIC WILL SPLIT WITH AN UPPER LOW CLOSING OFF AND
TAKING UP RESIDENCE OFF OF THE NORTHERN CALIFORNIA COAST EARLY NEXT
WEEK. THIS FEATURE WILL KEEP THE REGION IN SOUTH TO SOUTHWEST FLOW
ALOFT...WHICH WILL SERVE TO SEND MID-LEVEL MOISTURE INTO THE REGION.
MONDAY NIGHT LIKELY REMAINS DRY...BUT BY TUESDAY SOME PRECIPITATION
DEVELOPS INTO THE FORECAST AREA. WHILE SOME MODEL DIFFERENCES DO
REMAIN AND THERE IS SOME QUESTION OVER JUST HOW MUCH INSTABILITY
WILL BE PRESENT...ENOUGH SUPPORT FROM THE FORECAST MODELS TO EXTEND
THUNDERSTORM CHANCES OVER THE EASTERN PORTION OF THE FORECAST AREA
FOR TUESDAY AND WEDNESDAY.  THIS UPPER LOW REMAINS IN PLACE THROUGH
MIDWEEK...BEFORE SHIFTING ONSHORE AND INTO THE GREAT BASIN BY LATE
IN THE WEEK. TEMPERATURES WILL REMAIN WARMER THAN SEASONAL NORMALS
NEXT WEEK BUT GRADUALLY COOL DURING THE LAST FEW DAYS OF NEXT WEEK.
&&

.AVIATION...00Z TAF EXPECTATIONS...A WIDE SPREAD IN CONDITIONS AT
THIS HOUR AS SHOWERS ARE ENDING AT THE NORTH COAST AND ABOUT
REACHING THEIR PEAK STRENGTH INLAND. CENTRAL COAST HAS SEEN AN IFR
DECK PUSH ON TOP OF THE KONP VCTY. WILL CONTINUE TO SEE CONDITIONS
IMPROVE THIS EVENING AS MORE STABLE AIR UNDER NORTHWEST TO NORTH
FLOW DEVELOP. FEEL SKIES MAY CLEAR UP ENOUGH LATER OVERNIGHT SUCH
THAT A STRATUS DECK AT ROUGHLY 015-020 WILL DEVELOP AT MOST SITES.
AM EXPECTING BURNOFF TO OCCUR AROUND 18Z INLAND AND CLOSER TO 00Z
AT THE COAST. EXCEPTION MAY BE THE SOUTH WILLAMETTE VALLEY AND
KEUG WHERE NORTHERLY FLOW MAY PACK THE MOISTURE LONGER OVER THE
FIELD.

KPDX AND APPROACHES...BKN022-025 WILL BE POSSIBLE MAINLY THROUGH
01Z BUT SOME LINGERING SHOWERS MAY HANG ON AND BRING BRIEF DROPS
UNTIL
03Z. THEN EXPECT CIGS TO REMAIN 040-050 OR BETTER FOR SEVERAL
HOURS. HAVE REASONABLE CONFIDENCE A STRATUS DECK AROUND 020-025
WILL DEVELOP LATER OVERNIGHT AND REMAIN THROUGH ROUGHLY 18Z
BEFORE INVERSIONS LIFT AND THE DECK FAIRLY RAPIDLY BREAKS APART.
/JBONK

&&

.MARINE...OFFSHORE SWELL HASN'T REALLY REACHED 10 FT AND STILL
MAY NOT REACH 10 FT FOR THE COASTAL WATERS TONIGHT. HOWEVER...WILL
KEEP THE SCA FOR SEAS IN PLACE AS SEAS WILL BE FAIRLY STEEP WITH 9
FT AND 10-11 SEC PERIODS WONT TAKE MUCH OF A BOOST TO REACH SCA
CRITERIA FOR STEEP SEAS. STILL EXPECT A SEVERAL HOUR PERIODS WITH
WINDS GUSTING AROUND 25 KT. WINDS WILL EASE FOR A TIME SATURDAY
BUT THERMAL TROUGH/LOW PRESSURE OVER NORTHERN CALIFORNIA AND FAR
SOUTHERN OREGON WILL INDUCE MORE OF A SUMMERTIME NORTHERLY WIND
PATTERN BY SATURDAY EVENING AND CONTINUE THROUGH MUCH OF SUNDAY AS
WELL. STRONGEST WINDS WILL LIKELY BE LATE AFTERNOON THROUGH THE
EVENING.

AS THE WINDS PICK UP...SO WILL THE CHOPPY WIND DRIVEN
SEAS...REACHING ABOUT 8 TO 10 FT S OF NEWPORT AT TIMES IN THE
AFTERNOON/EVENINGS. WILL LIKELY NEED SMALL CRAFT ADVISORIES FOR
GUSTY WINDS AND/OR SEAS THIS WEEKEND...BUT WILL NOT ISSUE UNTIL
THE CURRENT SERIES OF ADVISORIES EXPIRE IN ORDER TO AVOID
CONFUSION. JBONK

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO 6 AM PDT 
     SATURDAY FOR WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR 
     FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 6 PM THIS EVENING 
     TO 6 AM PDT SATURDAY FOR WATERS FROM CAPE SHOALWATER WA TO 
     FLORENCE OR FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS FROM 6 PM THIS EVENING TO 3 AM 
     PDT SATURDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO 
     FLORENCE OR OUT 10 NM.

&&


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO 6 AM PDT 
     SATURDAY FOR WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR 
     FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 6 PM THIS EVENING 
     TO 6 AM PDT SATURDAY FOR WATERS FROM CAPE SHOALWATER WA TO 
     FLORENCE OR FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS FROM 6 PM THIS EVENING TO 3 AM 
     PDT SATURDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO 
     FLORENCE OR OUT 10 NM.

&&


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS THIS AFTERNOON THROUGH TONIGHT
  ON ALL COASTAL WATERS.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS TONIGHT ON THE OUTER
  COASTAL WATERS...OR FROM 10 TO 60 NM OFFSHORE. 

&&

$$ 

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND 

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.

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